Linux CIFS client, Windows 2012 CIFS file server => files not found?

[Kristian Rink <kawazu428-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Folks;

the last few years we've been locally serving files using a NetApp 
storage system exposing CIFS and several (Windows, Linux) clients 
mounting these shares in order to host data and run an internal business 
application.

The application itself (binaries, libraries, resources, a bunch of ksh 
scripts) entirely lives on the CIFS share. So far (having NetApp CIFS 
mounted), this worked on all machines.

Now, these CIFS shares are to be provided by a Windows 2012 Storage 
Server. Outcome: Linux machines can't run this application anymore. 
Having mounted the W2012 CIFS share, the application won't start 
complaining that some resources (scripts and libraries) are missing, 
even while they are obviously around and also, permission-wise, accessible.

It's difficult to really figure out what happens here. Basically, 
looking at strace output, it seems the application does stat64() one of 
these files which in both cases seems to provide a valid outcome...

stat64("/opt/.../file.oeb", {st_mode=S_IFREG|0755, st_size=36405, ...}) = 0

... but while mounting the share off the NetApp the application works as 
desired, mounting the share off the W2012 server the application will 
terminate here complaining about this particular resource missing.

Vague as it is, does anyone have any idea what could be causing this? 
I've been playing with various parameters of mount.cifs so far, but I'm 
not deep enough into either NetApps nor Windows 2012s understanding of 
CIFS to have an idea what might have changed here...

TIA,
Kristian